He was born Pierre Denis de Lagarde Boal on September 29, 1895, at Thonon-les-Bains, Haute-Savoie, France, to Theodore Davis Boal and his wife, Mathilde Marie Dolorès Denis de Lagarde. In 1925 his father was a lieutenant colonel in the 28th Infantry Division, a unit in the Army National Guard and the oldest division-sized unit in the United States armed forces.
Boal's French wife, Jeanne de Menthon, was a descendant of Bernard of Menthon, an 11th-century saint.[2] Their children included Mimi Lee, who served as the First Lady of Maryland from 1977 to 1979.[2]
He died at 3 p.m. of a "cerebral vascular accident" on May 24, 1966, at the American hospital on 63 Victor Hugo Boulevard, Neuilly-sur-Seine, France. After his death, his body was released to his wife Jeanne and transported from the Paris Orly Airport to Kennedy International Airport on its way to Boalsburg, Pennsylvania, for interment.